I got my DM42 in February, and it worked great. It's been in a box (off, of course) for March and April while I moved my office, and I just checked it out again. The calculator would not power up without USB attached. With USB, it operated just fine.

I removed the battery, which read near 0V. I placed a new good CR2032, which read 3.1V, but still no activity when I press ON. I tried resetting the calc via the reset button, but nothing. Again, the calc works when USB is attached.

Am having the same problems with batteries. Michael from Swiss Micros told me to update to firmware to 3.5. Did so but the battery voltage falls from 3v to low 2's within say a day. Wondering whether you found a solution to the problem? Thanks Les Cook (Australia).